The overall objective of the phase I program is to demonstrate the feasibility of newly developed advanced permeable membranes for the combined duties on military aircraft of nitrogen generation to inert fuel tanks and oxygen generation for pilot breathing in a unique system arrangement. These compact and lightweight membranes lend themselves to a more efficient obiggs/obogs design combination than feasible with previously tested membranes for on-board aircraft gas generation. The phase 1 program will focus on acquiring basic membrane performance data while operating in the dual obiggs/obogs role and on permeable membrane cartridge design and operating modes to determine the quality of the oxygen produced and to assess the overall system weight, space and bleed air requirements. One of the keys to being able to implement the dual obiggs/obogs concept is to demonstrate production of a suitable flow and quality of oxygen using the vented OEA from the obiggs as the feed gas to the obogs. In this manner the bleed air requirements will be minimized. The oxygen production may proceed by use of membrane cartridges as columns (i.e., single stage reflux systems), by use of pressurized staged cartridges or by a combination of these cartridge/operating mode options to produce the required oxygen flow/quality with the lowest weight/volume requirement. Thus, the phase 1 program will be geared at indicating the preferred configuration of the obogs portion of the system.